1. Field of Invention
The present invention relates generally to the field of computerized devices and user interfaces. More particularly, in one exemplary aspect, the present invention is directed to calibration of embedded interface operation, such as for example with respect to Embedded DisplayPort™ (eDP) implementations.
2. Description of Related Technology
The presentation of audio and visual elements has a direct impact on customer satisfaction. For example, many multimedia devices are widely judged (and purchased) according to qualities such as display quality, sound fidelity, smooth rendering, crispness of the display, lack of motion artifact or “jerkiness”, etc. Other areas of multimedia applications which affect consumers include interoperation (e.g., with other equipment, legacy standards, etc.), ease of use, cost, power consumption.
To these ends, audio/visual (A/V) interface technologies have evolved from simple display logic circuits into complex systems capable of, inter alia, platform-independent operation, networked operation, “plug and play” connection, etc. Moreover, current display interface technologies support seamless legacy display operation; i.e., newer functionality is layered over existing legacy protocols. For example, secondary data may be transmitted during time intervals which are otherwise ignored or not utilized by legacy devices.
DisplayPort™ is one example of a display interface technology referred to above. It is specified by the Video Electronics Standards Association (VESA). Current incarnations of the DisplayPort standard specify support for simple networking of digital audio/visual (A/V) interconnects, intended to be used primarily between an arbitrary assembly of multimedia “sources” (e.g., computers or CPUs) and “sinks” (e.g., display monitors or other video rendering devices, home-theater systems, etc.).
Extant DisplayPort technology is an extensible digital interface solution that is designed for a wide variety of performance requirements, and broadly supports inter alia, PCs, monitors, panels, projectors, and high definition (HD) content applications. Current DisplayPort technology is also capable of supporting both internal (e.g., chip-to-chip), and external (e.g., box-to-box) digital display connections. Examples of internal chip-to-chip applications include notebook PCs, which drive a display panel from a graphics controller, or display components from display controllers driving the monitor of a television. Examples of box-to-box applications include display connections between PCs and monitors, and projectors (i.e., not housed within the same physical device). Consolidation of internal and external signaling methods enables the “direct drive” of digital monitors. Direct drive eliminates the need for control circuits, and allows for among other things, less costly and reduced profile (e.g., slimmer or smaller form factor) display devices.
However, while extant DisplayPort technology is well suited for a wide range of applications, certain applications do not require the full functionality of DisplayPort. For example, Embedded DisplayPort (eDP) was developed specifically to enable standardized display interfaces for embedded-type fixed interfaces (e.g., for internally connecting a graphics card to laptop displays, tablet computer displays, etc.). Initial standards for eDP were largely based on the existing DisplayPort standard, however in subsequent standard releases, significant changes and optimizations have been added that further depart from traditional DisplayPort. One such area which has been left largely unchanged is the DisplayPort calibration sequence. The DisplayPort calibration process is designed to maximize the interoperability of DisplayPort sources and sinks while maintaining significant margin to compensate for cabling losses. Unlike DisplayPort, eDP is intended only for closed systems (i.e., systems that have essentially known sources, sinks and cable losses). Thus, existing schemes for eDP calibration do not have the same requirements for interoperability that the generic DisplayPort interfaces require.
Accordingly, improved solutions are required for Embedded DisplayPort (eDP) calibration. Specifically, such improved solutions should be optimized for link calibration between known eDP sources, eDP sinks, and cabling configurations. More generally, improved methods and apparatus are required for calibrating transceivers within closed systems. Such solutions should ideally offer improved performance, reduced manufacturing time, etc.